Diffusion bonding is a solid-state fusing technique used in metalworking, which is capable of joining similar and dissimilar metals. More specifically, diffusion bonding utilizes solid-state diffusion to make atoms of two solid metallic surfaces intermingle and cross-link over time. Diffusion bonding is typically implemented by applying high pressure and/or temperature to the materials to be bonded and is commonly used to fuse alternating layers of thin metal foils.
Some metals (e.g., aluminum) readily generate a heat-resistant oxide coating when exposed to atmospheric air. This oxide coating may interfere with effective diffusion bonding of the thin metal foils together. This is especially problematic when the metal has a relatively low melting temperature, such as aluminum, which limits the quantity of heat that can be added during diffusion bonding while preserving any fine features within the individual metal components. As a result, such metals are not typically diffusion bonded unless they are alloyed with other metals that resist oxidation and/or increase melting temperature before the diffusion bonding process.